Contactless battery system utilizing a bidirectional power converter

ABSTRACT

A bidirectional power converter circuit is controlled via a hysteresis loop such that the bidirectional power converter circuit can compensate for variations and even changes in transmit and receive coil locations without damaging components of the system. Because the bidirectional power converter is capable of both transmitting and receiving power (at different times), one circuit and board may be used as the main component in multiple wireless power converter designs. A first bidirectional power converter is employed in a sealed battery unit having no external electrical contacts. A second bidirectional power converter is employed in a corresponding cart bidirectional power converter assembly. The battery unit and the cart bidirectional power converter assembly cooperate to wirelessly transmit power from the battery unit to a load of the cart bidirectional power converter assembly and from a power source to the battery unit via the cart bidirectional power converter assembly.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/096,215 entitled Contactless Battery System Utilizing a BidirectionalPower Converter, filed Apr. 11, 2016, which claims priority to, andhereby incorporates by reference in its entirety, U.S. ProvisionalPatent Application Ser. No. 62/146,091 entitled “WIRELESS POWER SYSTEM”filed on Apr. 10, 2015.

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the reproduction of the patent document or the patentdisclosure, as it appears in the U.S. Patent and Trademark Office patentfile or records, but otherwise reserves all copyright rights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates generally to power converters. Moreparticularly, this invention pertains to bidirectional power convertersand sealed batteries.

Designing circuits and laying out printed circuit boards is a timeconsuming and expensive process. Further, having multiple circuits andboards requires tracking multiple revisions of multiple circuits andprinted circuit boards, which adds layers of complexity. However, incurrent power transfer circuit design techniques, circuit and boardlayouts are created for one specific purpose. Having multiple circuitsand board layouts, each with multiple revisions is therefore heretoforeunavoidable.

Wireless charging systems are limited by, inter alia, size, space, andtransmitter/receiver orientation limitations. That is, wireless chargingsystems for batteries have wireless chargers, but the batteries directlyphysically contact the circuits of the device powered by the battery.The battery is not fully wireless which can be advantageous in wet orsterile environments. Further, wireless charging systems are currentlylimited by distance and/or orientation. That is, in some systems atransmitter coil must nearly be in contact with a receiver coil (e.g.,laying a cell phone equipped with wireless charging capabilities on awireless charging pad). In these systems, the Z directional differentialbetween the transmitter coil and the receiver coil is therefore nearzero while the X and Y directional variations are within a margin oferror (e.g., the cell phone and its power receiving coil are within aspecified diameter of a transmitting coil or antenna of the chargingpad). In other systems, the Z directional differential between thetransmitter coil and the receiver coil may be substantial, but thetransmitter coil and the receiver coil must be located on the same axis(i.e., almost no variation in the X and Y directions between the coilsand no variation in pitch). If the pitch or X-Y translation is notaccurate, the transmitter may be damaged, requiring replacement of thetransmitter circuit board. Thus, wireless charging systems that cannotcompensate for variations in transmitter and receiver coil relativelocations are difficult to manage and repair, and they are not practicalfor many uses in the field.

BRIEF SUMMARY OF THE INVENTION

Aspects of the present invention provide a bidirectional power convertercircuit. The bidirectional power converter circuit is capable of bothtransmitting and receiving power, such that the bidirectional powerconverter circuit of the present invention may be used as the maincomponent in multiple wireless power converter designs. Thebidirectional power converter circuit is controlled via a hysteresisloop such that the bidirectional power converter circuit can compensatein near real time for variations and even changes in transmitter andreceiver coil locations without damaging any components of the system.In one aspect, a contactless battery unit incorporates a bidirectionalpower converter to provide a battery in a fully sealed housing with noexternal contacts to either a charger or a device to be powered by thebattery.

In one aspect, a battery unit includes a sealed housing, a battery, abattery management system, a digital Hall effect sensor, and amicroprocessor. The sealed housing has no external electrical contacts.The battery unit is configured to selectively store DC power andselectively provide DC power. The coil is enclosed by the sealedhousing. The bidirectional power converter has an AC terminal connectedto the coil, a DC input terminal, a DC output terminal, a directioncontrol, and a transmission unable input. The bidirectional powerconverter has a transmit mode operable to provide AC output power to thecoil from the battery and a receive mode operable to receive AC powervia the coil and provide a DC output to the DC output terminal. Thebattery management system is connected to the battery, the DC inputterminal, and the DC output terminal. The battery management system isresponsive to a chart signal to selectively provide DC power to thebattery for storage from the DC output of the bidirectional powerconverter and provide DC power received from the battery to the DC inputof the bidirectional power converter. The digital Hall effect sensor isconfigured to sense proximity of a permanent magnet of a cartbidirectional power converter assembly and to provide a binary presentsignal indicative of the proximity of the permanent magnet. Themicroprocessor is connected to the direction control of thebidirectional power converter, the transmission unable input of thebidirectional power converter, the digital Hall effect sensor, and thebattery management system. The microprocessor is configured to determinethe mode of the bidirectional power converter from the cartbidirectional power converter assembly. In the transmit mode, themicroprocessor sets the battery management system to provide DC powerfrom the battery to the DC input of bidirectional power converter byproviding the chart signal, sets the bidirectional power converter tothe transmit mode via the direction control input, and provides atransmit enable signal to the transmission unable input of thebidirectional power converter in response to receiving the binarypresent signal from the digital Hall effect sensor indicating thepresence of the permanent magnet of the cart bidirectional powerconverter assembly. In the receive mode, the microprocessor sets thebattery management system to provide DC power to the battery for storagefrom the DC output of the bidirectional power converter via the chartsignal, and sets the bidirectional power converter to the receive modevia the direction control input.

In another aspect, a cart bidirectional power converter assemblyincludes a cradle, a permanent magnet, a coil, a bidirectional powerconverter, and a microprocessor. The cradle is configured to receive thebattery unit. The permanent magnet is configured to be in proximity witha digital Hall effect sensor of the battery unit when the battery unitis in the cradle. The coil is configured to be aligned with a coil ofthe battery unit when the battery unit is in the cradle. Thebidirectional power converter is connected to the coil and configured toreceive power from the battery unit via the coil when the battery unitis in the cradle, a bidirectional converter of the battery unit is in atransmit mode, and the bidirectional power converter of the cartbidirectional power converter assembly is in a receive mode. Thebidirectional power converter is configured to provide power from a DCinput of the bidirectional power converter to the coil when thebidirectional power converter is in a transmit mode. The powerdistribution assembly is configured to provide power from the DC outputof the bidirectional power converter to a load of the cart bidirectionalpower converter when the power distribution assembly is not connected toa power source. The power distribution assembly is further configured toprovide power from the power source to a DC input of the bidirectionalpower converter and to load when the power distribution assembly isconnected to the power source. The power distribution assembly alsoprovides a mode signal as a function of whether the power distributionassembly is receiving power from the power source. The microprocessor isconnected to a directional control of the bidirectional power converterand to the power distribution assembly. The microprocessor is responsiveto the mode signal from the power distribution assembly to set a mode ofthe bidirectional power converter to a transmit mode when the powerdistribution assembly is receiving power from the power source and setsthe bidirectional power converter to receive mode when the bidirectionalpower converter is not receiving power from the power source. Themicroprocessor is further configured to communicate with amicroprocessor of the battery unit to set a mode of the bidirectionalpower converter of the battery unit to transmit when the powerdistribution assembly is not receiving power from the power source. Themicroprocessor also sets the mode of the bidirectional power converterof the battery unit to a receive mode when the power distributionassembly is receiving power from the power source.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of how FIGS. 1A to 1I fit together to form ablock diagram of one embodiment of a bidirectional power converter.

FIG. 1A is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1B is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1C is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1D is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1E is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1F is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1G is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1H is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 1I is a partial block diagram of the block diagram of thebidirectional power converter of FIG. 1.

FIG. 2 is a block diagram of how FIGS. 2A to FIGS. 2P fit together toform a partial schematic diagram of the bidirectional power converter ofFIG. 1.

FIG. 2A is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2B is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2C is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2D is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2E is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2F is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2G is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2H is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2I is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2J is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2K is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2L is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2M is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2N is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2O is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 2P is a partial schematic diagram of the bidirectional powerconverter of FIG. 2.

FIG. 3 is block diagram of how FIGS. 3A to 3V fit together to form apartial schematic diagram of the bidirectional power converter of FIGS.1 and 2.

FIG. 3A is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3B is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3C is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3D is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3E is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3F is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3G is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3H is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3I is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3J is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3K is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3L is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3M is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3N is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 30 is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3P is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3Q is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3R is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3S is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3T is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3U is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 3V is a partial schematic diagram of the bidirectional powerconverter of FIG. 3.

FIG. 4 is a block diagram of how FIGS. 4A to 4Z fit together to form apartial schematic diagram of the bidirectional power converter of FIGS.1, 2, and 3.

FIG. 4A is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4B is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4C is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4D is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4E is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4F is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4G is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4H is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4I is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4J is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4K is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4L is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4M is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4N is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4O is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4P is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4Q is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4R is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4S is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4T is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4U is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4V is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4W is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4X is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4Y is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 4Z is a partial schematic diagram of the bidirectional powerconverter of FIG. 4.

FIG. 5 is a block diagram of how FIGS. 5A to 5J fit together to form apartial schematic diagram of the bidirectional power converter of FIGS.1-4.

FIG. 5A is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5B is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5C is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5D is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5E is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5F is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5G is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5H is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5I is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 5J is a partial schematic diagram of the bidirectional powerconverter of FIG. 5.

FIG. 6 is a block diagram of how FIGS. 6A to 6U fit together to form acontactless battery system utilizing the bidirectional power convertersof FIGS. 1-5.

FIG. 6A is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6B is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6C is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6D is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6E is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6F is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6G is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6H is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6I is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6J is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6K is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6L is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6M is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6N is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6O is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6P is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6Q is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6R is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6S is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6T is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

FIG. 6U is a partial contactless battery system utilizing thebidirectional power converter of FIG. 6.

Reference will now be made in detail to optional embodiments of theinvention, examples of which are illustrated in accompanying drawings.Whenever possible, the same reference numbers are used in the drawingand in the description referring to the same or like parts.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of the embodiments described herein, anumber of terms are defined below. The terms defined herein havemeanings as commonly understood by a person of ordinary skill in theareas relevant to the present invention. Terms such as “a,” “an,” and“the” are not intended to refer to only a singular entity, but ratherinclude the general class of which a specific example may be used forillustration. The terminology herein is used to describe specificembodiments of the invention, but their usage does not delimit theinvention, except as set forth in the claims

The phrase “in one embodiment,” as used herein does not necessarilyrefer to the same embodiment, although it may. Conditional language usedherein, such as, among others, “can,” “might,” “may,” “e.g.,” and thelike, unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or states. Thus, such conditional language is notgenerally intended to imply that features, elements and/or states are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/orstates are included or are to be performed in any particular embodiment.

The terms “coupled” and “connected” mean at least either a directelectrical connection between the connected items or an indirectconnection through one or more passive or active intermediary devices.

The term “circuit” means at least either a single component or amultiplicity of components, either active and/or passive, that arecoupled together to provide a desired function.

The terms “switching element” and “switch” may be used interchangeablyand may refer herein to at least: a variety of transistors as known inthe art (including but not limited to FET, BJT, IGBT, JFET, etc.), aswitching diode, a silicon controlled rectifier (SCR), a diode foralternating current (DIAC), a triode for alternating current (TRIAC), amechanical single pole/double pole switch (SPDT), or electrical, solidstate or reed relays. Where either a field effect transistor (FET) or abipolar junction transistor (BJT) may be employed as an embodiment of atransistor, the scope of the terms “gate,” “drain,” and “source”includes “base,” “collector,” and “emitter,” respectively, andvice-versa.

The terms “power converter” and “converter” unless otherwise definedwith respect to a particular element may be used interchangeably hereinand with reference to at least DC-DC, DC-AC, AC-DC, buck, buck-boost,boost, half-bridge, full-bridge, H-bridge or various other forms ofpower conversion or inversion as known to one of skill in the art.

As used herein, “micro” refers generally to any semiconductor basedmicroelectronic circuit including, but not limited to, a comparator, anoperational amplifier, a microprocessor, a timer, an AND gate, a NORgate, an OR gate, an XOR gate, or a NAND gate.

Terms such as “providing,” “processing,” “supplying,” “determining,”“calculating” or the like may refer at least to an action of a computersystem, computer program, signal processor, logic or alternative analogor digital electronic device that may be transformative of signalsrepresented as physical quantities, whether automatically or manuallyinitiated.

To the extent the claims recited herein recite forms of signaltransmission, those forms of signal transmission do not encompasstransitory forms of signal transmission.

Referring now to FIGS. 1-5, in one embodiment, a bidirectional powerconverter 100 is operable to provide AC power to an AC terminal 102 ofthe bidirectional power converter 100 in a transmit mode of thebidirectional power converter 100. The bidirectional power converter 100is further operable to provide DC power at a DC output terminal 104 ofthe bidirectional power converter 100 in a receive mode of thebidirectional power converter 100. In one embodiment, bidirectionalpower converter 100 includes an oscillator 106, an amplifier 108, amodulator 110, a hysteretic receiver circuit 112, a transmit relay 114,a rectifier 116 a receive relay 118, and a hysteretic control circuit120. In one embodiment, the bidirectional power converter 100 includestwo generally independent sections, a transmitter section and a receiversection. The transmitter section and the receiver section areselectively connected to the DC output terminal 104 and AC terminal 102by a set of solid state relays (e.g., transmit relay 114 and receiverelay 118).

The oscillator 106 is configured to provide a drive signal at a basefrequency when the bidirectional power converter 100 is operating in thetransmit mode. In one embodiment, the base frequency of the oscillator106 is approximately 100 kHz. In one embodiment, the oscillator 106generates the carrier frequency at which power is transmitted by thebidirectional power converter transmitter section. In one embodiment,micro U17 of oscillator 106 is an industry standard 556 timer whichcontains two 555 timers. One timer of micro U17 is configured as a oneshot timer, and the other timer is a free running oscillator,oscillating at 100 KHz. The one shot timer of micro U17 guarantees a 50%duty cycle for the modulator 110 during startup of the transmittersection. Resistors R65 and R70 as well as capacitors C47 and C49 set thefree running frequency of 100 kHz (or some other base frequency).Resistors R67 and R68 and capacitor C44 set the one shot timer for aprecise 50% duty cycle out of pin 9 of the micro U17.

The amplifier 108 is configured to receive power from a power source viaDC input terminal 122 of the bidirectional power converter 100 andprovide an AC output signal to the AC terminal 102 of the bidirectionalpower converter 100 in response to receiving the drive signal when thebidirectional power converter 100 is operating in the transmit mode. Inone embodiment, the amplifier 108 is a full bridge amplifier. In oneembodiment, the amplifier 108 provides a differential output capable ofup to 500 W RMS. Power MOSFETS Q1/Q4 and Q5/Q6 (see FIG. 2) are drivenby a first micro U1 to form a first half bridge power amplifier HBPA1,and power MOSFETS Q9/Q12 and Q13/Q14 are driven by a second micro U10 toform a second half bridge power amplifier HBPA2. The outputs of thefirst half bridge power amplifier HBPA1 and the second half bridge poweramplifier HBPA2 combine at the load (i.e., at the AC output 102) at 180degrees out of phase to provide power drive at the load. Micros U1 andU10 provide fast turn on/off drive to their respective power MOSFETS toassure efficient switching operation. Micros U1 and U10 also providegalvanic isolation electrically isolating the input/output grounds.Micros U3 and U4 cooperate to provide dead-time control for powerMOSFETS Q1/Q4 and Q5/Q6 assuring that they are never on at the same timecausing a dead short for the power supply +PWR_TX. Micros U11 and U12provide the same functionality as micros U3 and U4 for Q9/Q12 andQ13/Q14. Micros U2, U9, U5, and U33 convert the four inputs to the fullbridge amplifier to the necessary drive to derive a differential ACoutput voltage at the load (i.e., AC output terminal 102). This part ofthe amplifier ensures that the output of each HBPA in the disable stateis ground, essentially keeping power MOSFETS Q5/Q6 for the first halfbridge power amplifier HBPA1 and power MOSFETS Q13/Q14 for the secondhalf bridge power amplifier HBPA2 in the on state.

The modulator 110 is configured to selectively provide the drive signalfrom the oscillator 106 to the amplifier 108 as a function of ahysteretic control signal when the bidirectional power converter 100 isoperating in the transmit mode. In one embodiment, the modulator 110 isan amplitude shift keyed modulator. The Amplitude Shift Keying Modulator110 provides a digitized version of AM (Amplitude Modulation) to thefull bridge amplifier 108, effectively keying on/off the full bridgeamplifier 108 dependent on the logic state of the feedback signal (i.e.,hysteresis control signal) received from a second bidirectional powerconverter configured as a receiver (i.e., in the receive mode). The AMOD110 effect is to keep the voltage generated at the DC output terminal ofthe second bidirectional power converter assembly output constant. TheAMOD 110 accepts four inputs FD_BCK (i.e., hysteretic control signal),100 KHz_OSC (i.e., drive signal) from the oscillator 106, ONE_SHOT(i.e., one shot signal) from the one shot timer 170, and SSL (i.e., thepulse width modulated signal) from the slow start logic circuit 172. TheAMOD 110 generates four outputs (i.e., two sets of differential outputs)to the full bridge amplifier 108: 100 KHz_OUT_MODULATED, 100KHz_OUT_MODULATED_N, TX_EN, TX_EN_N. The modulator enable signal(MODULATOR_EN) enables/disables the AMOD (modulator) 110. Once the AMOD110 is enabled, the drive signal from the oscillator 106 (100 KHz_OSC)drives CLK pins of micro U15 and micro U38, sequentially clocking thelogic state of the hysteresis control signal (FD_BCK), once the one shotsignal (ONE_SHOT) has settled to a logic 0 and the slow start circuit172 pulse width modulated signal (SSL) has settled to a logic 1. Amodulator internal signal 100 KHz_OUT_MODULATED is derived from microU38 and its inverted version from micro U35. The TX_EN and TX_EN_Nsignals are derived from the Q/Q_N pins of U15B. These outputs drive thefull bridge amplifier 108 and contain the feedback information from thesecond bidirectional power converter 100 configured as a receiver. Alogic 1 at D of micro U15A turns on the full bridge amplifier 108continuously while a logic 0 at D of micro U15A turns off the fullbridge amplifier 108 and turns on power MOSFETS Q5, Q6, Q13, and Q14 tokeep each half bridge power amplifier (i.e., HBPA1 and HBPA2) output atground potential.

The hysteretic receiver circuit 112 is configured to receive atransmitted control signal at the bidirectional power converter 100 andprovide the hysteretic control signal to the modulator 110 as a functionof the received, transmitted control signal when the bidirectional powerconverter 100 is operating in the transmit mode.

The transmit relay 114 is configured to electrically connect theamplifier 108 to the AC terminal 102 of the bidirectional powerconverter 100 when the bidirectional power converter 100 is operating inthe transmit mode and electrically disconnect the amplifier 108 from theAC terminal 102 of the bidirectional power converter 100 when thebidirectional power converter 100 is operating in the receive mode.

The rectifier 116 is configured to receive an alternating current powersignal from the AC terminal 102 of the bidirectional power converter 100and provide a DC output to the DC output terminal 104 of thebidirectional power converter 100 when the bidirectional power converter100 is operating in the receive mode. In one embodiment, the rectifier116 is a full wave rectifier. The rectifier 116 converts the AC powerreceived to pulsating DC at twice the incoming frequency. The rectifier116 is capable of receiving up to a maximum of 500 W RMS. The rectifieris implemented via diodes D14 through D19 and D22 through D27 (see FIG.4) connected in a full bridge rectifier configuration. A parallel diodecombination allows for higher power while keeping the efficiency high.In one embodiment, the diodes D14 through D19 and D22 through D27 are ofthe Schottky type for high speed operation.

The receive relay 118 is configured to enable the rectifier 116 toprovide the DC output to the DC output terminal 104 of the bidirectionalpower converter 100 when the bidirectional power converter 100 isoperating in the receive mode and prevent the rectifier 116 fromproviding the DC output to the DC output terminal 104 when thebidirectional power converter 100 is operating the transmit mode. In oneembodiment, the receive relay 118 is configured to enable the rectifier116 to provide the DC output to the DC output terminal 104 when thebidirectional power converter 100 is operating in the receive mode byelectrically connecting the rectifier 116 to the DC output terminal 104of the bidirectional power converter 100 when the bidirectional powerconverter 100 is operating in the receive mode. The receive relay 118 isfurther configured to prevent the rectifier 116 from providing the DCoutput to the DC output terminal 104 when the bidirectional powerconverter 100 is operating in the transmit mode by electricallydisconnecting the rectifier 116 from the AC terminal 102 of thebidirectional power converter 100 when the bidirectional power converter100 is operating in the transmit mode. In another embodiment, thereceive relay 118 is configured to prevent the rectifier 116 fromproviding the DC output to the DC output terminal 104 when thebidirectional power converter 100 is operating in the transmit mode byelectrically disconnecting the rectifier 116 from the DC output terminal104.

The hysteretic control circuit 120 is configured to monitor the DCoutput and transmit a control signal as a function of the monitored DCoutput when the bidirectional power converter 100 is operating in thereceive mode. In one embodiment, the hysteretic control circuit 120includes a hysteretic controller 132 and a transmitter. The hystereticcontroller 132 is configured to provide a logic signal. The logic signalis a 1st binary value when a voltage of the DC output from the rectifier116 is less than a predetermined threshold, and the logic signal is a2nd binary value when the voltage of the DC output is more than thepredetermined threshold. The 1st binary value is different than the 2ndbinary value. The response time of the hysteretic controller 132 isalmost instantaneous which gives the system (i.e., a pair ofbidirectional power converters 100, one operating in the transmit modeand one operating in the receive mode) excellent transient response atthe DC output terminal. The only delays involved in the control loop arethe propagation delays of the transmitter and hysteretic receivercircuit 112 and other system blocks of the power network (i.e.,modulator 116 and amplifier 108) which are very short. Another benefitof the hysteretic controller 132 and hysteretic receiver circuit 112 isthat the system has an unconditional operation stability, requiring nofeedback compensating components for stable operation. In oneembodiment, the hysteretic controller 132 further includes a feedbacknetwork. The feedback network provides a reduced voltage representativeof the DC output voltage of the rectifier 116, allowing for the outputof the bidirectional power converter to be adjusted anywhere between 12and 24 V DC as a function of the feedback network components (i.e.,resistors). Resistors R92, R95, and R101 (see FIG. 4) and capacitor C89provide the feedback network function. Resistors R92, R95, and R101 forma voltage divider that divides down the output voltage (i.e., the DCoutput voltage from the rectifier 116 and DC filter 186) to equal areference voltage applied to the hysteretic controller 132 by the linearregulator 182. At any time the output is regulated between 12-24V, thevoltage generated across R101 is always 2.5V which is equal to thereference voltage of micro U23A provided by the linear regulator 182.Capacitor C89 is used to pass some of the ripple of the DC output signalfrom the rectifier 116 and DC filter 186 to the input of the micro U23Ato speed up the switching action of the hysteretic controller 132,increasing efficiency and stability of the bidirectional powerconverter. In a 1st embodiment of the hysteretic controller 132, thetransmitter is a coil pulse driver 140 configured to receive the logicsignal and generate a magnetic field via a magnetic coupling coil. Thegenerated magnetic field is indicative of the logic signal. In the 1stembodiment, the hysteretic receiver circuit 112 includes a magneticsensor configured to receive a magnetic field and provide hystereticcontrol signal to the modulator 110 as a function of the receivedmagnetic field. In one version, a linear hall-effect sensor connects tojumper J3 of the bidirectional power converter 100. Micro U6A isconfigured as an AC coupled first-order low pass filter, for removingsome noise picked up by the hall-effect sensor. Micro U6B and comparatorU41A form a comparator circuit with a threshold set by micro U6B. Whenthe output of micro U6A equals the threshold set by micro U6B,comparator U41A sets its output (i.e., the hysteresis control signal) toa logic 1, and the comparator U41A sets its output (i.e., the hysteresiscontrol signal) to a logic zero when the output of micro U6A is lessthan the threshold set by micro U6B. In a 2nd embodiment, thetransmitter is a radio frequency (RF) transmitter configured to receivethe logic signal and transmit an RF signal via and antenna, wherein thetransmitted RF signal is indicative of the logic signal. In the 2ndembodiment, hysteretic receiver circuit 112 includes an RF receiverconfigured to receive an RF signal and provide the hysteretic controlsignal to the modulator 110 as a function of the received RF signal. Ina 3rd embodiment, the transmitter is an optical transmitter 142configured to receive the logic signal and transmit an optical signalvia an infrared emitter, wherein the transmitted optical signal isindicative of the logic signal. In the 3rd embodiment, the hystereticreceiver circuit 112 includes an infrared receiver 144 configured toreceive an optical signal and provide the hysteretic control signal tothe modulator 110 as a function of the received optical signal.

In one embodiment, the bidirectional power converter 100 furtherincludes a direction control input 130 configured to receive a directioncontrol signal. The direction control signal is provided to the transmitrelay 114 and the receive relay 118 to set the bidirectional powerconverter 100 in either the transmit mode or the receive mode.

In one embodiment, the bidirectional power converter 100 furtherincludes a coil 150 connected to the AC terminal 102 of thebidirectional power converter 100. The coil 150 is configured to receivethe AC output signal from the amplifier 108 and emit a correspondingelectromagnetic field when the bidirectional power converter 100 isoperating in the transmit mode. The coil 150 is further operable toconvert electromagnetic flux into an AC power signal when thebidirectional power converter 100 is operating in the receive mode. Inone embodiment, the coil 150 includes a wire coil 152 and a tuningcapacitor 154. The tuning capacitor 154 connects the wire coil 152 tothe AC terminal 102 of the bidirectional power converter 100.

In one embodiment, the bidirectional power converter 100 furtherincludes a DC charge control relay 160 (which can be external to othercomponents) including a unified DC terminal 162. The DC control relay160 is configured to connect to the DC input terminal 122 and the DCoutput terminal 104. The DC charge control relay 160 is configured toelectrically isolate the DC input terminal 122 from the DC outputterminal 104. The DC charge control relay 160 further electricallyconnects the DC input terminal 122 to the unified DC terminal 162 whenthe bidirectional power converter 100 is operating in the transmit modeand electrically connects the DC output terminal 104 to the unified DCterminal 162 when the bidirectional power converter 100 is operating inthe receive mode.

In one embodiment, bidirectional converter 100 further includes a slowstart circuit 172 and a one-shot timer 170. The slow start circuit 172is configured to provide a pulse width modulated signal that increasesfrom 0 to 100% duty cycle (i.e., “on” time) beginning when thebidirectional power converter 100 begins operating in the transmit mode.The rate of increase of the duty cycle of the pulse width modulatedsignal is generally linear. The effect of the pulse width modulatedsignal (SSL) from the slow start circuit 172 is to control the amount oftime the amplifier 108 remains in the on-state. This function is onlyused initially when the bidirectional power converter 100 is enabled totransmit for the first time (i.e., at each startup of the bidirectionalpower converter 100 as a transmitter). The pulse width modulated signal(SSL) varies the on-time of the amplifier 108 from 0 (fully off) to 1(fully on continuously) by controlling the on-time at the modulator 110,effectively ramping up the voltage received at a second bidirectionalpower converter 100 configured as a receiver until a set regulatedvoltage (i.e., a target output voltage) is reached. Once the set voltageis reached, the output of the SSL remains at a logic 1. In oneembodiment, of the slow start circuit 172, micro U16B is configured as asaw-tooth oscillator. The output of micro U16B, taken across capacitorsC41 and C42, is fed to PWM comparator U16A. A linear DC voltage isgenerated across a capacitor bank (i.e., capacitors C35, C36, C37, C38,and C39) by feeding the capacitor bank a constant current generated byswitch Q18. This linear generated DC voltage is compared in PWMcomparator U16A to the saw-tooth like ramp voltage generated by microU16B and a pulse width modulated signal is generated by PWM comparatorU16A to provide to the modulator 110.

The one-shot timer 170 is configured to provide a one-shot signal to themodulator 110 (and the one shot signal is “on”) when the bidirectionalpower converter 100 begins operating in the transmit mode and for apredetermined period of time thereafter. Modulator 110 is furtherconfigured to provide the drive signal from the oscillator 106 toamplifier 108 when the pulse width modulated signal is on and at leastone of the hysteretic control signal and one-shot signal are “on.” Inone embodiment, the one shot timer 170 provides a precise timecontrolled “momentary-on” enable signal to the AMOD (i.e., modulator110) when the transmitter section is first enabled. If, in the timeframe generated by the one shot timer 170, a feedback signal (i.e.,hysteresis control signal) is not received by the bidirectional powerconverter 100, the one shot timer 170 terminates the transmission. Thatis, the modulator 110 ceases providing the drive signal from theoscillator 106 to the amplifier 108 because the modulator 110 isreceiving neither the hysteresis control signal nor the one shot signal.In addition, this embodiment permits the transmit section to terminateoperation in the event the feedback signal is interrupted, once it hasbeen received. Micro U42 (see FIG. 3) is the one shot timer 170 designedutilizing a standard 555 timer. The on-time of the one shot signal iscontrolled by resistor R146 and capacitors C133 and C134. The modulatorenable signal (MODULATOR_EN) provided by the control logic 176 triggersthe one shot timer 170 via pin 2 of micro U42 (i.e., 555 timer) throughswitch Q37.

In one embodiment, the bidirectional power converter 100 furtherincludes a temperature sensor 174 and control logic 176. The temperaturesensor 174 is configured to monitor a temperature of the amplifier 108and provide a temperature sensing signal indicative of the monitoredtemperature. The control logic 176 is configured to provide a modulatorenable signal to the modulator 110 as a function of the temperaturesensing signal and the direction signal such that the modulator enablesignal is provided when the direction control signal sets thebidirectional power converter 100 in the transmit mode and thetemperature sensing signal is indicative of a temperature less than apredetermined temperature. The modulator 110 does not provide the drivesignal from the oscillator 106 to the amplifier 108 when the modulator110 is not receiving a modulator enable signal. In one embodiment, thetemperature sensor 174 monitors the full bridge amplifier 108 viathermal coupling of the temperature sensor 174 to the full bridgeamplifier 108. When the temperature at the full bridge amplifier 108reaches a threshold set by the temperature sensor 174, the temperaturesensor 174 sets its output disabling the full bridge amplifier 108 viathe modulator 110. When the temperature at the full bridge amplifier 108drops to a safe value, the temperature sensor 174 re-enables the fullbridge amplifier 108 via the modulator 110. The status of thetemperature sensor 174 can be obtained from the signal connector atpin-6. In one embodiment, micro U14 is an integrated circuitmanufactured by Maxim Integrated™ capable of +/−0.5 degree C. accuracyand a temperature range of −20 to 100 degree C. Resistors R51, R53, andR53 and switch Q17 set the two set points for micro U14. In oneembodiment, the set points disable at 80 C and enable at 40 C. In oneembodiment of the control logic 176, the control logic 176 takes in thesignals from the temperature sensor 174 (TEMP_EN_DIS) and the TX_ONsignal from signal connector pin-2 and generates a single enable/disablesignal (MODULATOR_EN) for the modulator 110. Micros U39 and U40 providethe logic function needed for the control logic 176. When the outputfrom the temperature sensor 174 (TEMP_EN_DIS) is logic 0 and transmitterenable signal from pin 2 of the signal connector (TRANS_EN) is logic 1,modulator enable signal (MODULATOR_EN) is a logic 1, enabling thetransmit function of the bidirectional power converter 100.

In one embodiment, the bidirectional power converter 100 furtherincludes a switching regulator 180. The switching regulator 180 isconfigured to generate bias voltages when the bidirectional powerconverter 100 is receiving power from the power source at the DC inputterminal 122 of the bidirectional power converter 100. Switchingregulator 180 provides at least one of the generated bias voltages tothe oscillator 106, the amplifier 108, the modulator 110, the hystereticreceiver circuit 112, and the transmit relay 114, the slow start circuit172, the one-shot timer 170, and the temperature sensor 174. In oneembodiment, the switching regulator 180 implements a buck switching typeregulator.

In one embodiment, the bidirectional power converter 100 furtherincludes a linear regulator 182. The linear regulator 182 is configuredto receive the DC output from the rectifier 116 and provide biasvoltages to the hysteretic control circuit 120 when the bidirectionalpower converter 100 is operating in the receive mode.

In one embodiment, the bidirectional power converter 100 furtherincludes a DC filter 186 configured to relay the DC output provided bythe rectifier 116 to the DC output terminal 104. The DC filter 186converts the pulsating DC output from the rectifier 116 to a fixed DCvoltage with relatively low ripple. Capacitor bank C76 through C80charge to the peak value of the rectified AC voltage (i.e., thepulsating DC output provided by the rectifier 116) and supply power tothe load (i.e., the DC output terminal) during certain times (i.e., thetroughs) of the pulsating DC output signal provided by the rectifier116.

In one embodiment, the bidirectional power converter 100 furtherincludes a plurality of isolators 190. The plurality of isolators 190are configured to isolate the DC input terminal 122 from the AC terminal102 and the AC terminal 102 from the DC output terminal 104 of thebidirectional power converter 100 such that the bidirectional powerconverter 100 is an isolated power source in both the transmit mode andthe receive mode.

Referring to FIG. 6, a pair of bidirectional power converters are usedto form a contactless battery system. The contactless battery systemincludes a battery unit 302 and a cart bidirectional power converterassembly 304. The battery unit 302 includes a sealed housing (not shown)configured to enclose all of the components of the battery unit 302. Thesealed housing has no external electrical contacts. The battery unit 302further includes a battery 322, a coil 330, a battery bidirectionalpower converter 400 (substantially identical to the bidirectional powerconverter 100 discussed above), a battery management system 310, adigital Hall effect sensor 306, and a battery microprocessor 308. Thebattery 322 is enclosed by the sealed housing and is configured toselectively store DC power and selectively provide DC power. The batterybidirectional power converter 400 has an AC terminal 402 connected tothe coil 330, a DC input terminal 404, a DC output terminal 406, adirection control 408, and a transmission enable input 410 the batterybidirectional power converter 400 has the transmit mode operable toprovide AC output power to the coil 330 from the battery 322 and areceive mode operable to receive AC power via the coil 330 and provide aDC output to the DC output terminal 406.

The battery management system 310 is connected to the battery 322, theDC input terminal 404, and the DC output terminal 406. The batterymanagement system 310 is responsive to charge signal to selectivelyprovide DC power to the battery 322 for storage from the DC output 406of the bidirectional power converter 402 provide DC power received fromthe battery 322 to the DC input 404 of the battery bidirectional powerconverter 400.

The digital Hall effect sensor 306 is configured to sense proximity of apermanent magnet 312 of the cart bidirectional power converter assembly700 and provide a binary present signal to the battery microprocessor308 indicative of the proximity of the permanent magnet 312 to thedigital Hall effect sensor 306.

Battery microprocessor 308 is connected to the direction control 408,the transmission enable input 410, the digital Hall effect sensor 306,and the battery management system 310. The battery microprocessor 308 isconfigured to determine a mode of the battery bidirectional powerconverter 400 from the cart bidirectional power converter assembly 700.In the transmit mode, battery microprocessor 308 is operable to set thebattery management system 310 to provide DC power from the battery 322to the DC input 404 of the battery bidirectional power converter 400 byproviding the charge signal to the battery management system 310.Battery microprocessor 308 is further operable in the transmit mode toset the battery bidirectional power converter 400 to the transmit modevia the direction control input 408 and provide a transmit enable signalto the transmission enable input 410 of the battery bidirectional powerconverter 400 in response to receiving the binary present signal fromthe digital Hall effect sensor 306 indicating the presence of thepermanent magnet 312 of the cart bidirectional power converter assembly700. In the receive mode, the battery microprocessor 308 sets thebattery management system 310 to provide DC power to the battery 322 forstorage from the DC output 406 of the battery bidirectional powerconverter 400 via the charge signal and sets the battery bidirectionalpower converter 400 to the receive mode via the direction control input408. In one embodiment, the battery microprocessor 308 of the batteryunit 302 is operable to communicate with a cart microprocessor 314 ofthe cart bidirectional power converter assembly 304 via Bluetooth todetermine which mode to set the battery bidirectional power converter400 of the battery unit 302. In one embodiment of the battery unit 302battery bidirectional power converter 400, control logic 176 isconfigured to receive a temperature sensing signal and the transmissionenable signal and provide a modulator enable signal to a modulator ofthe battery bidirectional power converter 400 as a function of thetemperature sensing signal and the transmission enable signal. That is,control logic 176 provides the modulator enable signal to the modulator110 only when the temperature sensing signal indicates that thetemperature of the amplifier 108 is within a predetermined range.

Referring now to the cart bidirectional power converter assembly 304,the cart bidirectional power converter assembly 304 includes the cradle(not shown) configured to receive the battery unit 302, the permanentmagnet 312, a coil 332, the cart bidirectional power converter 700, thepower distribution assembly 316, and the cart microprocessor 314. Thepermanent magnet 312 is configured to be in proximity with the digitalHall effect sensor 306 when the battery unit 302 is in the cradle. Thecoil 332 is configured to be aligned with the coil 330 of the batteryunit 302 when the battery unit 302 is in the cradle. The cartbidirectional power converter 700 of the cart bidirectional powerconverter assembly 304 is connected to the coil 332 and configured toreceive power from the battery unit 302 via the coil 332 when thebattery unit 302 is in the cradle, a bidirectional power converter ofthe battery unit 400 is in a transit mode, and the cart bidirectionalpower converter 700 is in a receive mode. The cart bidirectional powerconverter 700 of the cart bidirectional power converter assembly 304 isfurther configured to provide power from a DC input 702 of the cartbidirectional power converter 700 to the coil 332 when the cartbidirectional power converter 700 is in the transmit mode. The powerdistribution assembly 316 is configured to provide power from the DCoutput 704 of the cart bidirectional power converter 700 to a load 320of the cart bidirectional power converter 700 when the powerdistribution assembly 316 is not connected to a power source 318. Thepower distribution assembly 316 is further configured to provide powerfrom the power source 318 of the DC input 702 of the bidirectional powerconverter at the load 320 when the power distribution assembly 316 isconnected to the power source 318. The power distribution assembly 316is further configured to provide a mode signal as a function of whetherthe power distribution assembly 316 is receiving power from the powersource 318. The cart microprocessor 314 is connected to a directionalcontrol 706 of the bidirectional power converter and to the powerdistribution assembly 316. The cart microprocessor 314 is responsive tothe mode signal from the power distribution assembly 316 to set a modeof the cart bidirectional power converter 700 to transmit mode when thepower distribution assembly 316 is receiving power from the power source318 and set the cart bidirectional power converter 700 to a receive modewhen the cart bidirectional power converter 700 is not receiving powerfrom the power source 318. The cart microprocessor 314 is furtherconfigured to communicate with the battery microprocessor 308 of thebattery unit 302 to set a mode of the battery bidirectional powerconverter 400 of the battery unit 302 to transmit mode when the powerdistribution assembly 316 is not receiving power from the power source318. The cart microprocessor 314 is further configured to set the modeof the battery bidirectional power converter 400 of the battery unit 302to receive mode when the power distribution assembly 316 is receivingpower from the power source 318.

It will be understood by those of skill in the art that information andsignals may be represented using any of a variety of differenttechnologies and techniques (e.g., data, instructions, commands,information, signals, bits, symbols, and chips may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof). Likewise, thevarious illustrative logical blocks, modules, circuits, and algorithmsteps described herein may be implemented as electronic hardware,computer software, or combinations of both, depending on the applicationand functionality. Moreover, the various logical blocks, modules, andcircuits described herein may be implemented or performed with a generalpurpose processor (e.g., microprocessor, conventional processor,controller, microcontroller, state machine or combination of computingdevices), a digital signal processor (“DSP”), an application specificintegrated circuit (“ASIC”), a field programmable gate array (“FPGA”) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. Similarly, steps of a method orprocess described herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Althoughembodiments of the present invention have been described in detail, itwill be understood by those skilled in the art that variousmodifications can be made therein without departing from the spirit andscope of the invention as set forth in the appended claims.

A controller, processor, computing device, client computing device orcomputer, such as described herein, includes at least one or moreprocessors or processing units and a system memory. The controller mayalso include at least some form of computer readable media. By way ofexample and not limitation, computer readable media may include computerstorage media and communication media. Computer readable storage mediamay include volatile and nonvolatile, removable and non-removable mediaimplemented in any method or technology that enables storage ofinformation, such as computer readable instructions, data structures,program modules, or other data. Communication media may embody computerreadable instructions, data structures, program modules, or other datain a modulated data signal such as a carrier wave or other transportmechanism and include any information delivery media. Those skilled inthe art should be familiar with the modulated data signal, which has oneor more of its characteristics set or changed in such a manner as toencode information in the signal. Combinations of any of the above arealso included within the scope of computer readable media. As usedherein, server is not intended to refer to a single computer orcomputing device. In implementation, a server will generally include anedge server, a plurality of data servers, a storage database (e.g., alarge scale RAID array), and various networking components. It iscontemplated that these devices or functions may also be implemented invirtual machines and spread across multiple physical computing devices.

This written description uses examples to disclose the invention andalso to enable any person skilled in the art to practice the invention,including making and using any devices or systems and performing anyincorporated methods. The patentable scope of the invention is definedby the claims, and may include other examples that occur to thoseskilled in the art. Such other examples are intended to be within thescope of the claims if they have structural elements that do not differfrom the literal language of the claims, or if they include equivalentstructural elements with insubstantial differences from the literallanguages of the claims.

It will be understood that the particular embodiments described hereinare shown by way of illustration and not as limitations of theinvention. The principal features of this invention may be employed invarious embodiments without departing from the scope of the invention.Those of ordinary skill in the art will recognize numerous equivalentsto the specific procedures described herein. Such equivalents areconsidered to be within the scope of this invention and are covered bythe claims.

All of the compositions and/or methods disclosed and claimed herein maybe made and/or executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of the embodiments included herein, it willbe apparent to those of ordinary skill in the art that variations may beapplied to the compositions and/or methods and in the steps or in thesequence of steps of the method described herein without departing fromthe concept, spirit, and scope of the invention. All such similarsubstitutes and modifications apparent to those skilled in the art aredeemed to be within the spirit, scope, and concept of the invention asdefined by the appended claims.

Thus, although there have been described particular embodiments of thepresent invention of a new and useful CONTACTLESS BATTERY SYSTEMUTILIZING A BIDIRECTIONAL POWER CONVERTER it is not intended that suchreferences be construed as limitations upon the scope of this inventionexcept as set forth in the following claims.

What is claimed is:
 1. A battery unit comprising: a sealed housing withno external electrical contacts; a battery enclosed by the sealedhousing, wherein the battery is configured to selectively store directcurrent (DC) power and selectively provide DC power; a coil enclosed bythe sealed housing; a bidirectional power converter having an ACterminal connected to the coil, a DC input terminal, a DC outputterminal, a direction control, and a transmission enable input, whereinthe bidirectional power converter has a transmit mode operable toprovide AC output power to the coil from the battery and a receive modeoperable to receive AC power via the coil and provide a DC output to theDC output terminal; a battery management system connected to thebattery, the DC input terminal, and the DC output terminal, wherein thebattery management system is responsive to a charge signal toselectively provide DC power to the battery for storage from the DCoutput of the bidirectional power converter and to provide DC powerreceived from the battery to the DC input of the bidirectional powerconverter; a digital hall effect sensor configured to sense proximity ofa permanent magnet of a cart bidirectional power converter assembly andprovide a binary presence signal indicative of the proximity of thepermanent magnet; and a microprocessor connected to the directioncontrol of the bidirectional power converter, the transmission enableinput of the bidirectional power converter, the digital hall effectsensor, and the battery management system, wherein the microprocessor isconfigured to determine a mode of the bidirectional power converter fromthe cart bidirectional power converter assembly, and in the transmitmode: set the battery management system to provide DC power from thebattery to the DC input of the bidirectional power converter byproviding the charge signal; set the bidirectional power converter tothe transmit mode via the direction control input; and provide atransmit enable signal to the transmission enable input of thebidirectional power converter in response to receiving the binarypresence signal from the digital hall effect sensor indicating thepresence of the permanent magnet of the cart bidirectional powerconverter assembly; and, in the receive mode: set the battery managementsystem to provide DC power to the battery for storage from the DC outputof the bidirectional power converter via the charge signal; and set thebidirectional power converter to the receive mode via the directioncontrol input.
 2. The battery unit of claim 1, wherein themicroprocessor of the battery unit is operable to communicate with amicroprocessor of the cart bidirectional power converter assembly viaBluetooth to determine in which mode to set the bidirectional powerconverter of the battery unit.
 3. The battery unit of claim 1, whereinthe bidirectional power converter comprises a control logic configuredto receive a temperature sensing signal and the transmission enablesignal and provide a modulator enable signal as a function of thetemperature sensing signal and the transmission enable signal.
 4. Thebattery unit of claim 1, wherein the bidirectional power converter isoperable to provide alternating current (AC) power at an AC terminal ofthe bidirectional power converter in the transmit mode of thebidirectional power converter and provide direct current (DC) power atthe DC output terminal of the bidirectional power converter in thereceive mode, said bidirectional power converter comprising: anoscillator configured to provide a drive signal at a base frequency whenthe bidirectional power converter is operating in the transmit mode; anamplifier configured to receive power from a power source via the DCinput terminal of the bidirectional power converter and provide an ACoutput signal to the AC terminal of the bidirectional power converter inresponse to receiving the drive signal when the bidirectional powerconverter is operating in the transmit mode; a modulator configured toselectively provide the drive signal from the oscillator to theamplifier as a function of a hysteretic control signal when thebidirectional power converter is operating in the transmit mode; ahysteretic receiver circuit configured to receive a transmitted controlsignal at the bidirectional power converter and provide the hystereticcontrol signal to the modulator as a function of the received,transmitted control signal when the bidirectional power converter isoperating in the transmit mode; a transmit relay configured toelectrically connect the amplifier to the AC terminal of thebidirectional power converter when the bidirectional power converter isoperating in the transmit mode and electrically disconnect the amplifierfrom the AC terminal of the bidirectional power converter when thebidirectional power converter is operating in the receive mode; arectifier configured to receive an alternating current power signal fromthe AC terminal of the bidirectional power converter and provide the DCoutput to the DC output terminal of the bidirectional power converterwhen the bidirectional power converter is operating in the receive mode;a receive relay configured to enable the rectifier to provide the DCoutput to the DC output terminal of the bidirectional power converterwhen the bidirectional power converter is operating in the receive modeand prevent the rectifier from providing the DC output to the DC outputterminal when the bidirectional power converter is operating in thetransmit mode; and a hysteretic control circuit configured to monitorthe DC output and transmit a control signal as a function of themonitored DC output when the bidirectional power converter is operatingin the receive mode.
 5. The battery unit of claim 4, wherein thehysteretic control circuit comprises: a hysteretic controller configuredto provide a logic signal, wherein the logic signal is a first binaryvalue when a voltage of the DC output is less than a predeterminedthreshold and the logic signal is a second binary value when the voltageof the DC output is more than the predetermined threshold and whereinthe first binary value is different than the second binary value; and acoil pulse driver configured to receive the logic signal and generate amagnetic field via the magnetic coupling coil, wherein the generatedmagnetic field is indicative of the logic signal; and the hystereticreceiver circuit comprises a magnetic sensor configured to receive amagnetic field and provide the hysteretic control signal to themodulator as a function of the received magnetic field.
 6. The batteryunit of claim 4, wherein the modulator is an amplitude shift keyedmodulator.
 7. The battery unit of claim 4, wherein the amplifier is afull bridge amplifier.
 8. The battery unit of claim 4, wherein therectifier is a full wave rectifier.
 9. A cart bidirectional powerconverter assembly comprising: a cradle configured to receive a batteryunit; a permanent magnet configured to be in proximity with a digitalhall effect sensor of the battery unit when the battery unit is in thecradle; a coil configured to be aligned with a coil of the battery unitwhen the battery unit is in the cradle; a bidirectional power converterconnected to the coil and configured to receive power from the batteryunit via the coil when the battery unit is in the cradle, abidirectional power converter of the battery unit is in a transmit mode,and the bidirectional power converter is in a receive mode; and toprovide power from a DC input of the bidirectional power converter tothe coil when the bidirectional power converter is in a transmit mode; apower distribution assembly configured to: provide power from a DCoutput of the bidirectional power converter to a load of the cartbidirectional power converter when the power distribution assembly isnot connected to a power source; provide power from the power source tothe DC input of the bidirectional power converter and to the load whenthe power distribution assembly is connected to the power source; andprovide a mode signal as a function of whether the power distributionassembly is receiving power from the power source; and a microprocessorconnected to a directional control of the bidirectional power converterand to the power distribution assembly, wherein the microprocessor isresponsive to the mode signal from the power distribution assembly toset a mode of the bidirectional power converter to a transmit mode whenthe power distribution assembly is receiving power from the power sourceand set the bidirectional power converter to a receive mode when thebidirectional power converter is not receiving power from the powersource, and wherein the microprocessor is configured to communicate witha microprocessor of the battery unit to set a mode of the bidirectionalpower converter of the battery unit to a transmit mode when the powerdistribution assembly is not receiving power from the power source andto set the mode of the bidirectional power converter of the battery unitto a receive mode when the power distribution assembly is receivingpower from the power source.
 10. The cart bidirectional power converterassembly of claim 9, wherein the bidirectional power converter isoperable to provide alternating current (AC) power at an AC terminal ofthe bidirectional power converter in a transmit mode of thebidirectional power converter and provide direct current (DC) power atthe DC output terminal of the bidirectional power converter in a receivemode, said bidirectional power converter comprising: an oscillatorconfigured to provide a drive signal at a base frequency when thebidirectional power converter is operating in the transmit mode; anamplifier configured to receive power from a power source via the DCinput terminal of the bidirectional power converter and provide an ACoutput signal to the AC terminal of the bidirectional power converter inresponse to receiving the drive signal when the bidirectional powerconverter is operating in the transmit mode; a modulator configured toselectively provide the drive signal from the oscillator to theamplifier as a function of a hysteretic control signal when thebidirectional power converter is operating in the transmit mode; ahysteretic receiver circuit configured to receive a transmitted controlsignal at the bidirectional power converter and provide the hystereticcontrol signal to the modulator as a function of the received,transmitted control signal when the bidirectional power converter isoperating in the transmit mode; a transmit relay configured toelectrically connect the amplifier to the AC terminal of thebidirectional power converter when the bidirectional power converter isoperating in the transmit mode and electrically disconnect the amplifierfrom the AC terminal of the bidirectional power converter when thebidirectional power converter is operating in the receive mode; arectifier configured to receive an alternating current power signal fromthe AC terminal of the bidirectional power converter and provide a DCoutput to the DC output terminal of the bidirectional power converterwhen the bidirectional power converter is operating in the receive mode;a receive relay configured to enable the rectifier to provide the DCoutput to the DC output terminal of the bidirectional power converterwhen the bidirectional power converter is operating in the receive modeand prevent the rectifier from providing the DC output to the DC outputterminal when the bidirectional power converter is operating in thetransmit mode; and a hysteretic control circuit configured to monitorthe DC output and transmit a control signal as a function of themonitored DC output when the bidirectional power converter is operatingin the receive mode.
 11. The cart bidirectional power converter assemblyof claim 10, wherein the hysteretic control circuit comprises: ahysteretic controller configured to provide a logic signal, wherein thelogic signal is a first binary value when a voltage of the DC output isless than a predetermined threshold and the logic signal is a secondbinary value when the voltage of the DC output is more than thepredetermined threshold and wherein the first binary value is differentthan the second binary value; and a coil pulse driver configured toreceive the logic signal and generate a magnetic field via the magneticcoupling coil, wherein the generated magnetic field is indicative of thelogic signal; and the hysteretic receiver circuit comprises a magneticsensor configured to receive a magnetic field and provide the hystereticcontrol signal to the modulator as a function of the received magneticfield.
 12. The cart bidirectional power converter assembly of claim 10,wherein the modulator is an amplitude shift keyed modulator.
 13. Thecart bidirectional power converter assembly of claim 10, wherein theamplifier is a full bridge amplifier
 14. The cart bidirectional powerconverter assembly of claim 10, wherein the rectifier is a full waverectifier.